Many of optically active lactone derivatives represented by formula (II): ##STR3## wherein R.sup.1 represents an alkyl group having from 1 to 10 carbon atoms or a substituted or unsubstituted phenyl group; and * indicates an asymmetric carbon atom, are important per se as various insect pheromones or perfumes. Known processes for synthesizing these compounds include (1) a process starting with naturally occurring optically active substances (see Agric. Biol. Chem., Vol. 51, p. 635 (1987)), (2) a process comprising reduction of .gamma.-keto acids by using yeast (see Appl. Microbiol., Vol. 11, p. 389 (1963)), and (3) a process comprising optical resolution of racemates (see JP-A-55-43053, the term "JP-A" as used herein means an "unexamined published Japanese patent application").
With respect to process (3), it is known that racemic .gamma.-butyrolactone is obtained by, for example, hydrogenating maleic acid and/or maleic anhydride in the presence of a ruthenium catalyst, such as a phosphonium chloride, primary to tertiary phosphine hydrochloride or quaternary phosphoniumhydrochloride of ruthenium (see JP-A-2-200680).
Process (1) using a naturally occurring substance as a starting material involves many steps and complicated operations. Process (2) using microorganisms has not yet succeeded to achieve a high optical purity. Process (3) is disadvantageous in that an equivalent amount of an optically active compound is required and that a resolution efficiency reached is poor.
Hence, it has been demanded to establish a process for synthesizing a desired optically active .gamma.-butyrolactone derivative at a higher optical purity through a reduced number of steps.